This simple Digital Thermometer project use NTCs as the temperature sensor and microcontroller AVR ATmega 8 as main processor. This thermometer can be used as a standalone thermometer with LCD display or it can be read out with a PC running Linux, Windows, MacOSX or Solaris. For reading the temperatures no special drivers are needed.
In the past to interfacing with microcontroller many people always used rs232 communication with the UART that is included in the microcontroller. It requires an additional MAX232 chip, 4 extra capacitors and an external crystal oscillator for the microcontroller. But this Simple Digital Thermometer use connectivity via I2C because it is reliable, really easy to build and no more extra component.
Digital Thermometer Documentation Detail